Throttle butterflies with position feedback in internal combustion engines are operated with the help of controlling and adjusting algorithms. These algorithms ensure that the set position for the throttle butterfly requested by the driver is adjusted quickly and precisely. This is preset, for example by displacement of the accelerator by the driver of a motor vehicle.
The set position of the throttle butterfly is characterized by a control value. This control value is made up of a pilot value and a regulator intervention of a fed-back regulator on the throttle butterfly. Therefore, in order to regulate the position of the throttle butterfly or of an actuator quickly, it may be advantageous to know how the control value and the position resulting therefrom react to each other. A precisely known behavior means that the part of the fed-back adjustment on the control value is reduced in favor of the pilot control.
The pilot control may have the advantage over adjustment that it is proactive and inherently allows the throttle butterfly or the actuator to be adjusted more quickly.
Manufacturing tolerances, environmental influences and aging influence the relation between the pilot value and the position of the actuator or the throttle butterfly position. Therefore the pilot value must be adapted in order to know exactly the pilot value required for a flap position.
DE-A-36 12 905 C2 discloses an adaptive adjustment, in which the sensor values pertaining to the limit stops are learned. A linear interpolation is performed between the sensor values of the limit stops in order to determine the value pairs that lie therebetween. DE-A-35 10 176 A1, DE-A-40 05 255 C2 and DE-A-36 12 905 C2 describe a further control alternative. Here, for example, the control value for a requested set position is taken from an engine operating map. If the position achieved by the control value does not correspond with the set position, then a corresponding readjustment is made. The readjustment is recorded in a correction characteristic curve and is arranged downstream of the engine operating map in the further method. This is designed to reduce the time and effort needed for the readjustment. This correction characteristic curve also takes into account marginal conditions such as the temperature for example.